\(\left[{}\begin{matrix}v_{AB}=\dfrac{s_{AB}}{t}=\dfrac{1,8}{\dfrac{1}{10}}=18\left(\dfrac{km}{h}\right)\\v_{BC}=\dfrac{s_{BC}}{t}=\dfrac{2,2}{\dfrac{5}{60}}=26,4\left(\dfrac{km}{h}\right)\\v_{tb}=\dfrac{s_{AB}+s_{BC}}{t_{AB}+t_{BC}}=\dfrac{1,8+2,2}{\dfrac{1}{10}+\dfrac{5}{60}}=\dfrac{240}{11}\left(\dfrac{km}{h}\right)\end{matrix}\right.\)